As the capacity of batteries for electric vehicles has become higher, the way of cooling and heating the battery is changing into water cooling type. The change from air-cooling of lower-capacity batteries to the water-cooling type has increased efficiency of battery cooling systems but lowered heating efficiency of a battery left under a low temperature as compared to the existing heating wire type and has also increased consumption power.
In a case of heating the battery during low-current charging, it is often the case that heating current increases relative to charging current. It leads to a phenomenon that charging of the battery is stopped without proceeding, or that energy is consumed even while the battery is being charged.
Even if the battery's energy is properly used to heat itself, by the nature of In Cable Control Box (ICCB) charging that takes about 10 hours minimum, the temperature of the battery is likely to drop again at a time of completion of charging, and to prevent this, continuous heating is required.
In the meantime, as the battery's cell density increases, the output power (or power performance) at low temperatures is not enough, and this may be prevented by heating the battery.
Accordingly, appropriate distribution from within a limited current between charging and heating is required.